New Member

Recently my 98 GSX Limited took on water because both siphon tubes in the jet nozzle (to the rear of the impeller) had fallen out. My engine took on a lot of water so I followed the shop manual to clear the water out. The manual instructs you to check and change the crankcase oil if it has become fouled by water. It is this procedure that I will demonstrate in this guide, all without removing any parts from the machine. (Unless you consider the seat a part)

Prior to this, I had cleared my cylinders of all water. This is pretty straight forward and there is lots of info available on these boards on how to do this. The not-so-talked about procedure is checking the crankcase oil. the pictures below show you how bad the oil can get if water does get into the crankcase. It isn't the easiest thng to do because of the access to it, but I would not skip checking this out if your 787/947/951 engine takes on a lot of water. (I am not sure what the procedure is for newer model engines)

So first thing is getting the supplies. In addition to your typical tools, you will need:

SAE 30 Motor Oil

#6 Hex Wrench

Means to remove old oil and add new oil

To remove the old oil and add the new, I bought a Flavor Injector at Wal-Mart for $4. This is located in the kitchen utensils area is is normally used to inject marinade into meats.

Notice the sharp tip, the hole is located well above that so we will have to cut it down.

NOTE: ** Be sure when you cut it, there is no loose metal pieces that could fall into your crankcase.

I would avoid taking out the spark plugs. Even though it would give yourself more room to work, something small could fall in since you will be working directly above it.

Ok, so now we have to locate the hex nut we want to remove and I removed a few hoses as well to gain better access to the hex nut. You can try at first to leave the hoses attached and remove them only if you find they are limiting you based on the tools you are using. The following image shows their locations.

If you follow both red arrows till they meet, this would be the location of the hex nut (Red dot). The nut faces up and slightly towards the starboard side of the ski. All of the dots here are locations on the opposite side of the engine from this view.

This is the hex nut that we are looking for. Once you find it, you may want to spray some lube on it so that when it is time to get it off, your lube has soaked in a bit and should make it easier to remove it.

So the first thing I did was remove the water return hose, which is one of the main water hoses that runs to the rear of the ski. You just need a screwdriver, remove the clamp and push the hose to the side, out of the way.

Next, I removed a small, black water line used to remove water from the bottom of the cylinders. It's location is pointed out in one of the photos above. It is typically held on by a small zip tie, cut it and pull the hose.

Close-up view of the small, black water line which drains the lower portion of the cylinders.

Once I got those hoses out of the way, I cut a zip tie that held the steering cable in place so that it had more room to move around. The steering cable laid directly across the top of the hex nut we need to remove (at least in my machine).

Now, its time to remove the hex nut. get your #6 hex wrench (I used an allen wrench) and try to get in there with it. To gain leverage, I used a small metal tube from a bottle jack, and hammered it down so it fit snuggley onto the allen wrench so that there was no play in it.

You may have to get creative here,the hex nut is NOT easy to access, and range of motion is limited. A medium sized extension on a ratchet wrench would probably do the trick as well.

Unless you are already very familiar with this engine, you may have to feel around for awhile to find this bolt. You will not be able to see this bolt directly while the engine is in the ski. You could use a light and a mirror to see it, but you will have to put them down when you are actually trying to get in there.

Once, I got the bolt loose, I continued to remove it by hand. There definitely was a lot of water in my crankcase and built up pressure because once I got the bolt all the way out, the force of water shooting out of the crackcase blasted the bolt out of my hand and it fell directly below the engine. A magnetic extension arm would not pick it up as it was covered with oily water. I raised the front of the waverunner, tried every angle and evenually got it.

Finally, the prize.

Now that we got the bolt off, use whatever you got to drain/siphon the old oil out. Be careful to not let any foreign object fall into the small hole. the Flavor Injector I bought worked very well. It even had measurement lines on it so I knew exactly how much oil I was putting in. The 947/951 engine needs 40mL of SAE 30 oil.

Definitely water fouled oil.

New oil going in. I did two "injections" this size.

So, once you get your oil in, put the hex bolt back on, re-attach the small black hose, and larger water hose. Attach the spark plug caps, and fire it up.

Total time to do this was just over an hour, but I spent at least 15 minutes trying to get the damn hex bolt out from under the engine.

That would depend on the engine configuration in your challenger. They did make a dual 787 engine model, which does need this procedure performed here, but the "nut" is a bit different. The 787 has both a drain plug, and a plug on top to add/check oil.

I think the 99 challenger's may also have a M2 Jet drive motor configuration. In that case, you do not need to perform this procedure.

The pre-'97 787/800 motors have the counterbalance chambers and are filled with oil when the engine is built. However, they lack the drain plug and fill plugs necessary to perform this procedure on a fully assembled motor. So, if your engine fills with water, your option is pull the motor apart :ack: or deal with it and hope for the best. You could drill & tap your own access hole, but unless you have the motor out for other maintenace, I wouldn't bother. Also, you risk damaging your case, so you better know what you are doing.

From '97 and onward, the 787/800 had a drain plug and a fill plug added to the motor to allow this procedure to be performed without tearing the engine apart. So, if you do have a 787 with these access plugs, you should add this procedure to your yearly maintenance (suggested if you ride 50+ hours) or every 100 hours.

The topside access to this chamber on the 787/800 is located in a different area and is not the same hex screw you see here in this guide for the 947/951. As mentioned, the 787/800 also has a drain plug on the lower side of the counterbalance chamber for easier draining.

The 787/800 also uses slightly less oil, 30mL as opposed to the 40mL in the 947/951.

Premium Member

OK, I read this. My 1996 GTX - 787 engine filled with water on July 1st of 2011. I drained it all and it runs great as of today.
I've used it several times.
Do I need to drain and refill the oil of the counterbalance gears. gaaad i hope not! ! ! !

New Member

OK, I read this. My 1996 GTX - 787 engine filled with water on July 1st of 2011. I drained it all and it runs great as of today.
I've used it several times.
Do I need to drain and refill the oil of the counterbalance gears. gaaad i hope not! ! ! !

Well, since you have a 96 GTX, you would not be able to do this procedure, even though you may need to. The only way to fill the counterbalance area of the '96 787/800 motors is to tear the engine apart since there are no external openings to access it. In 1997, they started producing the 787/800 engines with external access holes to service the counterbalance area.

Allen sockets can be sourced at various parts stores. That and a wobble extension may save your knuckles. Also, if there is any pressure, it may be easier to handle. They are availible in standard and metric. Make sure you have the right one in your hand.

New Member

Kudos on the great info and pics redman. Ditto on the 6mm allen socket and universal joint or wobble extension mentioned above. Also, the flavor injector is key to this procedure. I used that with a little modification as described and pictured below. With all tools in hand, seat off and allen screw visually located I completed this in about 10 minutes without removing any hoses.

After cutting the flavor injector tube above the uppermost hole, I stripped a 4" piece of insulation off of a #10 copper wire and added it to the end of the flavor injector tube to make certain I was getting to the bottom of things (pun intended). I ended up getting 20mL of oil out of the cavity according to the graduations on the injector. It was dirty, but thankfully no sign of water. Since I was dealing with a 2000 model GTX which had almost certainly never had this done, I replaced the 20mL with 25mL of fresh 75W-90 synthetic gear oil (same thing I just put in the jet drive reservoir). I was afraid of overfilling. Next year I will do this again and see how much I'm able to pull out using the same procedure and maybe add a few mL more.

I used this setup to get to the allen bolt. 6mm socket on universal joint adapter with 10" extension.

Premium Member

Being this post is on the '98, Here is a write by a Famous Seadoo Industry Leader BILL O'NEIL, Watercraftmajic, California:

Do not look at the prices for the FI hoses without a cardiologist standing nearby.

The 1998 947 engines were the ones that would lose the mainbearings up front behind the flywheel. They had plastic cages in them.
All Elko pistons are subject to skirts breaking off as they will bend inward when water gets trapped between the skirts and the clyinder liners. They slap for quite awhile before they break off and if you ignore the slapping pistons, you deserve what you get when they break.

Oem quality bearings and seals should go into any 947 rebuild. Caged wrist pin bearings do not belong in any recreational 947 engine.

The main reason I spent so many hours at the lake testing filters and rejetting specs is to eliminate premature piston failures, the extra rpm and speed was a by product of feeding the motor the fuel it needs to run cooler and to build more power, with a much richer upper midrange fuel curve.
In 1997.5, you did not even want to attempt to cruise at 3/4 throttle with the 947 engine as the leanest part of the fuel curve was just below full throttle. It would almost guarantee a piston failure in at least 50% of the prototype grey deck GSXL's.
Fortunetly, Sea Doo added piston to clyinder wall clearances, bigger carb jets and needle valves, lower PO pressure and they turned the carbs 180 degrees in 1998 after replacing way too many top ends for free.

Forged pistons will hold up to some slapping for quite awhile, whereas the die cast Elko pistons will not hold up very long with a slapping piston or two.

Alot of rod failures are because idiots try riding the boat above idle speed right after rolling it over or swamping it and not removing the sparkplugs to pump the water out of the bottom of the motor. The water gets sucked up into the combustion chamber at higher rpm where the piston can hydrolock and bend the rod below it. Most riders do not realize it when they have lost a couple hundred rpm and they continue to ride the boat normally with a bent rod in it. The next thing you hear is a huge clunk and the motor stops turning. The rod will break half way up the rod and the lower piece will puncture the cases and usually wipe out at least the reeds and the surrounding aluminum reed opening. I have seen them break the starters off and ruin that side of the cases too. I cannot express how many 947 rust bucket engines we see each year in the shop with rods hanging out of them.

IMO, most of the above, other than the plastic ball retainers in the bearings, and the tendency to sieze pistons at less than full throttle when the 947's were introduced, are the owners or the riders fault.

Take a lightweight aluminum casting and put a 78mm crank in it and 88mm pistons on it, producing about 130 hp out in the water where it is vunerable to having water enter it, and you have the perfect storm. 130 hp in a recreational package that small and lightweight is a really big deal if you think about it.

Does anyone remember Sarge who has spent the past 15 years on misc forums ? He had a 1996 XP and then a 1998 XPL. He was retired military and spent almost every warm day riding his watercraft on a river in Connecticut. The last time I heard he had over 350 trouble free hours on his 947 engine, and I believe about the same on his 787 engine. He is now trying his best to wearout an RXP 4 Tech engine. I sold him lot's of parts like the 947 rejetting kit and filters, Solas impellors and nozzels for his '96 XP and a few other gadgets. The key to his success was fogging and regular maintence and allways running an oem exhaust system.

My own 947's were all heavily modified and rarely got more than 25 -40 hours on them before I tore the clyinder off to replace the pistons and wrist bearings. But I did run the crap out of a couple of my big bore rec motors for quite awhile without breaking them before I sold them off a year or two later.

I have found the above very true and Noteworthy for owners reading this great informative thread!
Bills86e

New Member

Thats really a great effort for making people understand how to change the oilin crankcase and that too making it visually by keeping all these images makes learning even more interesting. great work keep posting such images in future too regarding other engine works too.

New Member

For some reason this has been popping up no matter where I go. As far as I know, no water has ever entered the engine. I've had water inside the hull but not in the engine. I really considering doing this do to the fact it is 14 years old. Yes, No, Maybe, or hell no???? Thanks.

Member

My 98 GTX LTD got water in engine compartment the same way, through siffon tunes missing. Not much water got in before I noticed it, should I do this procedure? Seems like it might be peace of mind for me and may save my engine if there is water in there and if not I'm good for a long time and really not to expensive for peace of mind.

New Member

Recently my 98 GSX Limited took on water because both siphon tubes in the jet nozzle (to the rear of the impeller) had fallen out. My engine took on a lot of water so I followed the shop manual to clear the water out. The manual instructs you to check and change the crankcase oil if it has become fouled by water. It is this procedure that I will demonstrate in this guide, all without removing any parts from the machine. (Unless you consider the seat a part)

Prior to this, I had cleared my cylinders of all water. This is pretty straight forward and there is lots of info available on these boards on how to do this. The not-so-talked about procedure is checking the crankcase oil. the pictures below show you how bad the oil can get if water does get into the crankcase. It isn't the easiest thng to do because of the access to it, but I would not skip checking this out if your 787/947/951 engine takes on a lot of water. (I am not sure what the procedure is for newer model engines)

So first thing is getting the supplies. In addition to your typical tools, you will need:

SAE 30 Motor Oil

#6 Hex Wrench

Means to remove old oil and add new oil

To remove the old oil and add the new, I bought a Flavor Injector at Wal-Mart for $4. This is located in the kitchen utensils area is is normally used to inject marinade into meats.

Notice the sharp tip, the hole is located well above that so we will have to cut it down.

NOTE: ** Be sure when you cut it, there is no loose metal pieces that could fall into your crankcase.

I would avoid taking out the spark plugs. Even though it would give yourself more room to work, something small could fall in since you will be working directly above it.

Ok, so now we have to locate the hex nut we want to remove and I removed a few hoses as well to gain better access to the hex nut. You can try at first to leave the hoses attached and remove them only if you find they are limiting you based on the tools you are using. The following image shows their locations.

If you follow both red arrows till they meet, this would be the location of the hex nut (Red dot). The nut faces up and slightly towards the starboard side of the ski. All of the dots here are locations on the opposite side of the engine from this view.

This is the hex nut that we are looking for. Once you find it, you may want to spray some lube on it so that when it is time to get it off, your lube has soaked in a bit and should make it easier to remove it.

So the first thing I did was remove the water return hose, which is one of the main water hoses that runs to the rear of the ski. You just need a screwdriver, remove the clamp and push the hose to the side, out of the way.

Next, I removed a small, black water line used to remove water from the bottom of the cylinders. It's location is pointed out in one of the photos above. It is typically held on by a small zip tie, cut it and pull the hose.

Close-up view of the small, black water line which drains the lower portion of the cylinders.

Once I got those hoses out of the way, I cut a zip tie that held the steering cable in place so that it had more room to move around. The steering cable laid directly across the top of the hex nut we need to remove (at least in my machine).

Now, its time to remove the hex nut. get your #6 hex wrench (I used an allen wrench) and try to get in there with it. To gain leverage, I used a small metal tube from a bottle jack, and hammered it down so it fit snuggley onto the allen wrench so that there was no play in it.

You may have to get creative here,the hex nut is NOT easy to access, and range of motion is limited. A medium sized extension on a ratchet wrench would probably do the trick as well.

Unless you are already very familiar with this engine, you may have to feel around for awhile to find this bolt. You will not be able to see this bolt directly while the engine is in the ski. You could use a light and a mirror to see it, but you will have to put them down when you are actually trying to get in there.

Once, I got the bolt loose, I continued to remove it by hand. There definitely was a lot of water in my crankcase and built up pressure because once I got the bolt all the way out, the force of water shooting out of the crackcase blasted the bolt out of my hand and it fell directly below the engine. A magnetic extension arm would not pick it up as it was covered with oily water. I raised the front of the waverunner, tried every angle and evenually got it.

This is the result of losing the bolt under the engine.

Finally, the prize.

Now that we got the bolt off, use whatever you got to drain/siphon the old oil out. Be careful to not let any foreign object fall into the small hole. the Flavor Injector I bought worked very well. It even had measurement lines on it so I knew exactly how much oil I was putting in. The 947/951 engine needs 40mL of SAE 30 oil.

Definitely water fouled oil.

New oil going in. I did two "injections" this size.

So, once you get your oil in, put the hex bolt back on, re-attach the small black hose, and larger water hose. Attach the spark plug caps, and fire it up.

Total time to do this was just over an hour, but I spent at least 15 minutes trying to get the damn hex bolt out from under the engine.